In message <
[email protected]>, Jim via groups.io
<james_buttons@...> writes
Thanks Dave.
?
I'll look into that next. During my initial testing I did look at
the freq. output of the oscillator and I didn't see anything that
looked outrageous re: actual vs. setting, but I didn't run the math
to see if in spec. I the cases where the input LED was on,
sometimes the oscillator freq was spot on and other frequencies
where the LED was on freqs. seemed off from spec, but not too far
off. I think it may be a little bit of both - notch filter center
freq. being off in some cases, oscillator freq. off in others.
?
I looked through the schematic at the section for the monitor
output and it's a simple path from the main meter circuitry (which
appears to be working) - just a resistor, fuse and then the
isolation relay. I hear the relay get activated/deactivated, so
once I have the unit open again I will probe that path and see
where the signal stops. I am hoping that it's just the 0.062A fuse.
?
?
I am going to let the unit "bake" for a week or so. After 24 hours
the freq. that starts requiring the vernier is now down from 3.5
KHz to 3.3 KHz.
?
Did I read somewhere where HP did not include the schematic for the
339A's oscillator itself in the service manual?
?
I think it is there are some versions for this unit online here and
there had one for years very reliable;!
Whilst your at it make sure of you change the power supply caps this
improved the distortion reading on mine by a decent amount supply ripple
i suppose?>.
--
Tony Sayer
